random: Add __gnu_cxx:normal_mv_distribution<> class.

	* include/ext/random: Add __gnu_cxx:normal_mv_distribution<> class.
	* include/ext/random.tccAdd out-of-line functions for
	__gnu_cxx::normal_mv_distribution<>.
	* testsuite/26_numerics/random/normal_mv_distribution/
	operators/equal.cc: New file.
	* testsuite/26_numerics/random/normal_mv_distribution/
	operators/serialize.cc: New file.
	* testsuite/26_numerics/random/normal_mv_distribution/
	operators/inequal.cc: New file.
	* testsuite/26_numerics/random/normal_mv_distribution/
	cons/default.cc: New file.
	* testsuite/26_numerics/random/normal_mv_distribution/
	cons/parms.cc: New file.
	* testsuite/26_numerics/random/normal_mv_distribution/
	requirements/explicit_instantiation/1.cc: New file.
	* testsuite/26_numerics/random/normal_mv_distribution/
	requirements/typedefs.cc: New file.

From-SVN: r190960